- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A highly sensitive optofluidic-gas sensor using two dimensional photonic crystals
摘要： Photonic crystals (PCs) are optical structures based on periodic arrays of dielectric materials. These structures enable the manipulation of photons as semiconductors do for electrons. Many optical devices with miniature sizes have been designed based on novel properties of PCs. In this paper, we proposed a new refractive index sensor with high sensitivity and high quality factor, which is implemented in a two dimensional PC with a hexagonal lattice structure. The proposed sensor has been constructed using a PC waveguide surrounded by two rows of ring-shaped holes. The emersion of Fabry-Perot interference pattern within the transmission band and its role in the determination of the features of the proposed refractive index sensor has been investigated. The finite-difference time-domain simulation results indicate that in the case of filling the holes of central waveguide and its surrounding ring-shaped holes by different materials with refractive indices from n = 1 to n = 1.5, a high sensitivity of 575 nm/RIU and a high quality factor of 7070 is achieved, which makes the proposed design applicable for liquid and also gas sensing.
关键词： sensing waveguide,quality factor,sensitivity,Fabry-Perot oscillation,gas sensor,photonic crystal
更新于2025-09-23 15:21:01
-
Focal Relationship Between Structure and Function Within the Central 10 Degrees in Glaucoma
摘要： PURPOSE. To investigate which measurements of inner macular thickness are the most useful for evaluating the focal relationship with visual sensitivity within the central 108 in glaucoma and which layers require correction for retinal ganglion cell (RGC) displacement. METHODS. Sixty eyes of 60 subjects with glaucoma were included. Sensitivity of each test point of 10-2 standard automated perimetry was compared with the thickness of the retinal nerve ?ber layer (RNFL), ganglion cell layer (GCL), GCLt inner plexiform layer (IPL), and RNFLtGCLtIPL (GCC), with and without RGC displacement, using Spearman’s rank correlation coef?cients. Visual sensitivity was evaluated by unlogged 1/Lambert (1/L) values. RESULTS. Retinal nerve ?ber layer thickness correlated signi?cantly with the sensitivities of all test points except for some in the papillomacular bundle region when adjusting for RGC displacement (rs ? 0.287–0.767, P < 0.05). In the central 5.88, the GCL and (GCLtIPL) thickness correlated signi?cantly with the sensitivities of all test points when adjusting for RGC displacement (GCL: rs ? 0.363–0.729, P < 0.01; (GCLtIPL): rs ? 0.359–0.715, P < 0.01). The GCC thickness correlated signi?cantly with the sensitivities of all 68 test points when adjusting for RGC displacement (rs ? 0.359–0.767, P < 0.01). RGC displacement improved the correlation between sensitivity and GCL, (GCLtIPL), and GCC in the central 4 points (GCL: rs ? from 0.270–0.470 to 0.421–0.540; (GCLtIPL): rs ? from 0.195–0.450 to 0.381–0.549; GCC: rs ? from 0.132–0.449 to 0.359–0.562). CONCLUSIONS. The GCC is the most useful parameter to evaluate structure and function within the central 108 in glaucoma. Adjusting for RGC displacement is essential to evaluate the relationship between structure of the GCL-related layer and function at the central macula.
关键词： focal relationship,RGC displacement,visual sensitivity,inner macular thickness
更新于2025-09-23 15:21:01
-
Electrolyte-Insulator-Semiconductor pH Sensors with Arrayed Patterns Manufactured by Nano Imprint Technology
摘要： This work focuses on the sensing properties of electrolyte-insulator-semiconductor (EIS) pH sensors with arrayed patterns manufactured by integrating nano imprint technology (NIL) and CMOS process. The arrayed patterns, made of line and square at about ～200–400nm with a width/space ratio of about ～1/1-1/2, were fabricated by NIL; followed by the manufacturing of the EIS sensors. The patterns were studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The sensors, with arrayed patterns, all exhibited higher sensitivity, lower hysteresis, and lower drift properties than the single one did. The effects of arrayed patterns (square or line) and pattern density on the sensing area were also investigated. With this approach, the sensors can be fabricated for future high performance biochemical sensing applications.
关键词： sensitivity,drift,arrayed patterns,nano imprint technology,pH sensors,electrolyte-insulator-semiconductor,hysteresis
更新于2025-09-23 15:21:01
-
Influence of Ag NPs on Silicon Nanocolumns NH <sub/>3</sub> Gas Sensors
摘要： Two NH3 gas sensor devices, Al/Si nanocolumns/n-Si/Al and Al/Ag NPs/Si nanocolumns/n-Si/Al hybrid structures, have been fabricated and tested. A bare silicon nanocolumns layer was synthesized by a laser-assisted electrochemical etching process in HF solutions. The surface morphology of bare Si nanocolumns was modified by incorporating Ag NPs into Si nanocolumns by simple and fast immersions methods in an aqueous solution of AgNO3 to synthesize a hybrid structure. Characteristic features of bare Si nanocolumns and hybrid structure were investigated using scanning electron microscopy, EDS analysis, FTIR spectra, X-ray diffraction, and photoluminescence spectra (PL). The electrical characteristics of sensors with and without NH3 gas were measured at room temperature. The results showed that the nanoparticles grain size, nature, specific surface area (S.S.A) of Ag NPs, and morphological structure of the Si nanocolumns strongly affected the property characteristics. A significant enhancement in sensitivity, response, and recovery times of gas sensor for a hybrid structure was realized after compared with Al/Si nanocolumns/n-Si/Al gas sensor due to the high specific surface area.
关键词： silicon nanocolumns,response time,NH3 gas sensor,sensitivity,Ag NPs,hybrid structure,recovery time
更新于2025-09-23 15:21:01
-
Disorganization of Retinal Inner Layers (DRIL) and Neuroretinal Dysfunction in Early Diabetic Retinopathy
摘要： To elucidate the relationship between disorganization of retinal inner layers (DRILs) and retinal function in diabetic patients without diabetic retinopathy (DR) and with nonproliferative DR, but without diabetic macular edema (DME). Fifty-seven participants with diabetes mellitus (DM) and 18 healthy controls underwent comprehensive ophthalmic examination, fundus photography, and spectral-domain optical coherence tomography. Scans of the fovea were evaluated for the presence of DRIL. Retinal function was evaluated using Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity, the quick contrast sensitivity function (qCSF) on the AST Sentio Platform, short-wavelength automated perimetry (SWAP), standard automated perimetry (SAP), and frequency doubling perimetry (FDP). ANOVA and Kruskal-Wallis were used to compare retinal function in subjects with and without DRIL. Tukey-Kramer test and Wilcoxon were used for post hoc analysis. DRIL was identi?ed in 9 of 57 diabetic subjects. DRIL subjects had higher body mass index and longer diabetes duration compared to diabetic subjects without DRIL (P ? 0.03 and P ? 0.009, respectively). Subjects with DRIL had reduced ETDRS visual acuity (P ? 0.003), contrast sensitivity function (P ? 0.0003), and SAP performance (PSD, P < 0.0001) compared to controls and diabetic subjects without DRIL. Structural analysis revealed inner retinal thinning, and some outer retinal thinning, associated with DRIL. Diabetic subjects with DRIL have reduced retinal function compared to those without DRIL, and defective retinal lamination may be an early cellular consequence of diabetes responsible for this in some patients. Following further longitudinal studies, DRIL may be a readily available and reliable structural biomarker for reduced retinal function in early diabetic neuroretinal disease.
关键词： perimetry,diabetic retinopathy,contrast sensitivity,DRIL,OCT
更新于2025-09-23 15:21:01
-
IN SITU SECOND-HARMONIC GENERATION CIRCULAR DICHROISM WITH SUBMONOLAYER SENSITIVTIY
摘要： In this work, we present an experimental setup for the in situ and ex situ study of the optical activity of samples, which can be prepared under ultra-high vacuum (UHV) conditions by second-harmonic generation circular dichroism (SHG-CD) over a broad spectral range. The use of a racemic mixture as a qualified reference for the anisotropy factor is described and, as an example, the chiroptical properties of 1.5 μm thick (multilayers) as well as sub-monolayer thin films of the R- and S-enantiomer of 1,1'-Bi-2-naphthol (BINOL) evaporated onto BK7 substrates were investigated.
关键词： Submonolayer sensitivity,Second-harmonic generation circular dichroism,Circular-linear dichroism
更新于2025-09-23 15:21:01
-
Optical coherence tomography parameters predictive of visual outcome after anti-VEGF therapy for retinal vein occlusion
摘要： Purpose: To determine the optical coherence tomography (OCT) parameters that are predictive of visual outcome after anti-VEGF therapy for a retinal vein occlusion (RVO). Methods: Fifty-seven eyes with macular edema (ME) secondary to a central or branch RVO treated with bevacizumab or ranibizumab were studied. Spectral-domain OCT and microperimetry were performed before, 1, 3, and 6 months after the treatment and at the final visit. Central retinal thickness (CRT), macular volume (MV), integrity of the external limiting membrane (ELM), ellipsoid zone (EZ), and foveal bulge (FB), and photoreceptor outer segment (PROS) length were determined. Results: The mean follow-up period was 17.8±11.5 months. In 46 of the 57 eyes, a resolution of the ME was achieved. The pretreatment CRT and MV, presence of intact ELM, EZ, and FB, and PROS length at the time of ME resolution were significantly correlated with the best-corrected visual acuity and retinal sensitivity at the final visit (P0.050). Multiple regression analyses showed that the pretreatment MV had the highest correlation with the posttreatment best-corrected visual acuity and retinal sensitivity (P0.050). Conclusion: The CRT, MV, ELM, EZ, FB, and PROS length are predictive factors for the visual outcome after anti-VEGF therapy for RVO.
关键词： spectral-domain optical coherence tomography,visual acuity,retinal sensitivity,anti-VEGF therapy,retinal vein occlusion
更新于2025-09-23 15:21:01
-
Semiconductor α-Fe <sub/>2</sub> O <sub/>3</sub> Hematite Fabricated Electrode for Sensitive Detection of Phenolic Pollutants
摘要： Hematite (α-Fe2O3) semiconductor is an abundant and non-toxic catalyst for different (photo)electrochemical reactions. In this work, a selective p-nitrophenol sensor was developed by fabricating a thin-layer of a glassy carbon electrode (GCE) with 5% nafion coating binders onto α-Fe2O3 thin film synthesized by a simple and inexpensive process. High sensitivity including long-term stability, and enhanced linear dynamic range, electrochemical performance towards p-nitrophenol were achieved by a reliable current-voltage method. A linear calibration curve was observed over a wide range of p-nitrophenol concentrations. Very low detection limit (0.6 ? 0.02 nM), good limit of quantification (2.0 nM) and high sensor sensitivity (K = 74.1 μA?cm(cid:0) 2) are calculated based on noise to signal ratio of ～ 3 N/S. Very importantly, the detection range covers over 7 orders of magnitude concentrations, from nM to mM. Figures of merits are comparable with best reported results whilst using a very simple device configuration. We show that hematite is an excellent material for the development of chemical sensors to detect hazardous compounds for environmental safety in a broad scale of concentrations.
关键词： Environmental safety,Sensitivity,p-Nitrophenol sensor,Hematite α-Fe2O3,Glassy carbon electrode
更新于2025-09-23 15:21:01
-
Modulation of localized surface plasmon resonances of a silver nanoparticle array upon the presence of MoS2 coatings or underlying thin films
摘要： There has been recently a growing interest in studying light-matter coupling using supported metallic nanostructures arranged into periodic arrays. The influence on the layer thickness of two-dimensional materials such as molybdenum disulfide MoS2 on the plasmonic behaviour of these arrays has become of great relevance due to the favorable bonding between S (sulfide atom) and metal atoms such as gold and silver as well as the variation of optical transition of MoS2 depending on the atomic thickness of the film. In this work, we have numerically studied the change in absorption spectra of an ordered array of silver nanoparticles AgNPs when attached to glass as well as to glass coated with different layers of MoS2. This arrangement was compared to an AgNPs attached to glass and post coated with MoS2 films of increasing thickness. It was shown that an overcoating of four MoS2 layers results in an increased plasmonic sensitivity compared to uncoated glass/AgNPs interface. Replacing the glass substrate by glass coated with MoS2 of different thickness and with added AgNPs shows a significant to the red shift with increasing MoS2 layers. This band is due to strong excitation-plasmon coupling of the silver lattice with MoS2 layers. Important is the fact that the electrical field is strongly enhanced beneath the MoS2/AgNPs barrier. One also observes a significant enhancement of the sensitivity. Hence, the design of more sensitive AgNPs/MoS2 based-plasmonic biosensors could be reached. Indeed, we show that AgNPs coating with few layers of MoS2 leads to approximately a 210.26% higher sensitivity.
关键词： Sensitivity,MoS2,Silver nanoparticle array,BioSensors,Localized surface plasmon resonance
更新于2025-09-23 15:21:01
-
3D Printed Instrumentation for Point-of-Use Leaky Waveguide (LW) Biochemical Sensor
摘要： High sensitivity force sensing is a desirable function of capacitance touch screen panels. In this paper, we report on a dynamic force detection technique by utilizing piezoelectric materials. The force-voltage responsivities are investigated for four widely used stack-ups, with various panel thicknesses and touch locations. Based on the theoretical analysis and simulation results, the maximum responsivity and the signal-to-noise ratio are achieved at 0.42 V/N and 59.1 dB, respectively. The proposed technique implements force sensing successfully, enhancing the human–machine interactivity experience.
关键词： Force sensing,sensitivity,capacitive touchscreen panel,piezoelectric film
更新于2025-09-23 15:19:57